Ablation catheters and systems including rotational monitoring means

ABSTRACT

The present disclosure provides an improved ablation catheter. In particular, the present disclosure provides an improved renal denervation ablation catheter and system including a catheter handle and a means for tracking, monitoring, and/or recording the circumferential angular history of the renal denervation ablation catheter handle. The renal denervation ablation catheters in accordance with the present disclosure are well-suited for use with a renal denervation ablation system that can record the circumferential angular history of the renal denervation catheter handle, and hence the circumferential angular ablation history of the catheter electrode within a vessel, and use this data in combination with other known information to estimate the percent circumferential denervation of the vessel.

BACKGROUND OF THE DISCLOSURE

a. Field of the Disclosure

The present disclosure generally relates to ablation catheters. In particular, the present disclosure relates to renal denervation ablation catheters and systems including a catheter handle and a means for tracking, recording, and/or monitoring the circumferential angular history of the renal denervation ablation catheter handle. The renal denervation ablation catheters in accordance with the present disclosure are well-suited for use with a renal denervation ablation system that can track and record the circumferential angular history of the renal denervation catheter handle, and hence the circumferential angular ablation history of the catheter electrode(s) within a vessel, and use this data in combination with other known information to estimate the percent circumferential denervation of the vessel.

b. Background Art

It is known that various ablation procedures for the ablation of perivascular renal nerves have been used for the treatment of hypertension, and specifically for drug-resistant hypertension. Generally, one or more radiofrequency electrodes are introduced into the body and fed into the renal artery and used to ablate the efferent and afferent nerves that generally run the length of the artery. In some cases, a single ablation procedure may include six to ten or more ablation areas along and around the wall of the artery. Typically, the doctor performing the procedure will ablate one discreet area of the artery and then pull the ablation electrode a desired distance lengthwise about the length of the artery and also rotate the handle of the catheter to move the ablation electrode circumferentially around the artery. In some cases, the doctor may move the ablation electrode circumferentially about 45 degrees around the artery wall between ablations. By varying the ablation treatment sites lengthwise down and circumferentially around the artery wall, the overall damage to the wall can be reduced or minimized while the overall ablation of the efferent and afferent nerves can still be substantially complete and effective.

During the ablation procedure, the doctor performing the procedure generally attempts to monitor and track all of the areas of the artery wall that have previously been ablated to avoid over-treatment of any one site. This monitoring and tracking should be done both along the length of the artery as well as around the circumference of the artery wall to ensure proper ablation of the arterial nerves and the best procedural results.

Based on the foregoing, it would be advantageous to provide a circumferential angle tracking device for tracking and recording the rotational history of a renal denervation catheter handle, and hence a renal denervation catheter electrode(s) directed thereby, to allow for more precise and thorough ablation of a renal artery and a reduced occurrence of artery damage due to over-ablation of a single spot. Additionally, it would be beneficial if the circumferential angle tracking device is easily integratable with both single and multiple-electrode ablation catheter systems.

SUMMARY OF THE DISCLOSURE

It is desirable to be able to provide a means for tracking, monitoring, and/or recording the rotational history of an ablation catheter handle, and specifically a renal denervation ablation catheter handle, and hence the ablation electrode(s) directed thereby, to allow for a more complete circumferential artery ablation and improved procedural outcomes. It is also desirable to provide methods of using the means for tracking, monitoring, and/or recording the rotational ablation history of an ablation catheter and methods of estimating the overall percent denervation of renal efferent and afferent nerves. The present disclosure is directed to various means for tracking, monitoring, and/or recording the rotational history of an ablation catheter handle, and specifically a renal ablation catheter handle such that the circumferential angle is recorded for each ablation made by the electrode so that a more complete and accurate total ablation procedure may be performed. The embodiments disclosed herein are applicable to both single-electrode and multiple-electrode ablation systems. The present disclosure is also directed to methods of tracking, monitoring, and/or recording the angular circumferential ablation history of an ablation catheter, and to methods of estimating the circumferential percent renal denervation for a renal artery.

The present disclosure is directed to an ablation catheter system comprising a catheter handle, an elongate catheter body, an electrode, and a means for tracking a circumferential rotational history of the catheter handle.

The present disclosure is further directed to a method for tracking the circumferential ablation history of a renal artery. The method comprises ablating at least two areas on the renal artery using an ablation system comprising an ablation catheter comprising a catheter handle, an elongate catheter body, an electrode, and a means for tracking a circumferential rotational history of the catheter handle, and recording the circumferential rotational history of the catheter handle for each ablation.

The present disclosure is further directed to a method for estimating the circumferential percent renal denervation for a renal artery. The method comprises performing at least two ablations on the renal artery using an ablation system comprising an ablation catheter comprising a catheter handle, an elongate catheter body, an electrode, and a means for recording a circumferential rotational history of the catheter handle, recording a circumferential angle for each ablation, and using an average ablation spot size, a diameter of the artery, and circumferential angle for each ablation to estimate the circumferential percent renal denervation for the artery.

It has been found that the rotational angular ablation history of an ablation electrode, and specifically a renal ablation electrode, can be tracked, monitored and/or recorded precisely by using a rotational monitoring device in combination with the catheter handle that directs the ablation electrode inside of the artery. By monitoring, tracking and/or recording the rotational history of the catheter handle that directs or “steers” the ablation electrode within the artery, the ablation history of the electrode can be precisely tracked and recorded allowing for the percent denervation of the artery to be estimated and monitored during the renal denervation procedure. By more closely monitoring and controlling the ablation history of the ablation electrode, a more precise and thorough ablation of the nerves in the renal artery can be accomplished resulting in improved patient outcomes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a steerable ablation catheter.

FIG. 2 shows a steerable ablation catheter including rotational monitoring means in accordance with one embodiment of the present disclosure.

FIG. 3 shows a steerable ablation catheter including rotational monitoring means in accordance with another embodiment of the present disclosure.

FIG. 4 shows a steerable ablation catheter including rotational monitoring means in accordance with yet another embodiment of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

The ablation catheters, and specifically the renal denervation ablations catheters, and related methods of the present disclosure provide an improved ablation catheter that can easily and accurately track, record, and/or monitor the angular rotational history of the catheter, and specifically the catheter handle, during an ablation procedure, such as a renal denervation ablation procedure. This angular rotational history is directly related to the rotational ablation history of the catheter electrode located within the body such that an operator of the catheter system can accurately track and determine the circumferential ablation history of an artery or other area being treated. With this circumferential ablation history, the operator can more readily ascertain whether a complete circumferential ablation of an artery has been made, and can also use this circumferential ablation history along with other known information to accurately estimate the percent of denervation of renal efferent and afferent nerves. This can lead to improved patient outcomes and improved safety.

Embodiments of the present disclosure provide specific improvements to an ablation catheter, and specifically to an ablation catheter for use in a renal denervation procedure. The ablation catheters of the present disclosure include a means for tracking a circumferential rotational history of the catheter handle such that the circumferential rotational history of the ablation electrode directed by the catheter handle within an artery is accurately known. The rotational monitoring means for tracking the circumferential history of the catheter handle may include a non-rotating rotational monitor (relative to the catheter handle) appropriately marked with angular measurements and configured such that the catheter handle may rotate within, or may include electronic or other means for rotational monitoring as described herein.

Referring now to FIG. 1, there is illustrated steerable ablation catheter 2 for ablating target tissue of a vessel of the body in accordance with one embodiment of the present disclosure. Although generally described herein in the context of a renal denervation catheter for the ablation of nerves in a vessel wall, steerable ablation catheter 2 may be any suitable ablation catheter conventionally known that may benefit from the rotational monitoring means as described herein. Steerable ablation catheter 2 includes catheter handle 10 and flexible elongate catheter body 4 having proximal end 6 and distal end 8. The length of steerable ablation catheter 2 is generally sufficient to access a target vessel of the body, such as a patient's renal artery, relative to a percutaneous access location. Steerable ablation catheter 2 also includes hub 12 operably connected to an inner lumen (not shown) within catheter handle 10 for insertion or delivery of catheter assemblies and wires as conventionally known. Steerable ablation catheter 2 further includes electrode 14 near distal end 8. Electrode 14 may be a single electrode, or may contain multiple electrodes as is known in the art. Catheter handle 10 is coupled to flexible elongate catheter body 4 such that a torque imparted to catheter handle 10 can be transmitted to flexible elongate catheter body 4, as well as to electrode 14 that is coupled to flexible elongate catheter body 4.

Referring now to FIG. 2, there is illustrated a first embodiment of the present disclosure wherein steerable ablation catheter 2 includes flexible elongate catheter body 4, catheter handle 10, and non-rotating rotational monitor 16 including angular markings 18, 20, 22, 24, 26, 28, 29, and 50 for tracking the rotational history of catheter handle 10. Catheter handle 10 further includes rotational angle indicator 32. Non-rotating rotational monitor 16 is mounted to catheter handle 10 such that when catheter handle 10 is rotated during an ablation procedure, catheter handle 10, including rotational angle indicator 32 easily rotates such that electrode 14 directed thereby rotates as well, but non-rotating rotational monitor 16 remains in a fixed, non-moveable position, such that rotational angle indicator 32 can be rotated around non-rotating rotational monitor 16 and its position noted by angular markings 18, 20, 22, 24, 26, 28, 29, and 50. This allows for precise tracking of the rotational history of catheter handle 10, and hence electrode 14 directed thereby, during an ablation procedure.

As noted above, during a renal denervation procedure a doctor will generally ablate multiple segments along and around the artery wall for several seconds to treat the efferent and afferent nerves that typically run the length of the artery. Treating the entire circumferential area of the artery is desirable and, as such, the doctor will typically rotate catheter handle 10 prior to each successive ablation treatment to move electrode 14 circumferentially around the interior of the artery. By including rotational angle indicator 32 on catheter handle 10 of steerable ablation catheter 2, a doctor can easily and accurately determine where, around the circumference of the artery, electrode 14 has traveled and provided ablation such that a more complete and thorough circumferential ablation of the artery can be accomplished during the procedure. For example, prior to any ablation, a doctor may set the rotational angle indicator 32 to the 0 degree angular marking 18 position, and then after a first ablation is made on a renal artery, the doctor may pull electrode 14 along the length of the artery a desired amount and then rotate catheter handle 10 45 degrees until rotational angle indicator 32 shows 45 degrees before a second ablation is done to direct electrode 14 a known amount about the circumference of the artery wall. After the second ablation, the doctor may again pull electrode 14 along the length of the artery a desired amount and then rotate catheter handle 10 another 45 degrees until rotational angle indictor 32 shows 90 degrees before a third ablation is done. This process may be used successively throughout the entire ablation procedure to improve the circumferential ablation history of the procedure. As will be recognized by one of skill in the art, the actual amount of rotation of electrode 14 about the circumference of a vessel wall prior to each ablation may be more or less than 45 degrees without departing from the scope of the present disclosure. Also, each successive amount of rotation of electrode 14 about the circumference of a vessel may be the same or different.

In one specific embodiment using non-rotating rotational monitor 16 as described above, non-rotating rotational monitor 16 is wired or otherwise connected through steerable ablation catheter 2, such that the readings from non-rotating rotational monitor 16 may be transmitted to a visual medium for a doctor to monitor during a procedure. In this specific embodiment, as catheter handle 10 of steerable ablation catheter 2 is rotated during the procedure, the angle of rotation is not only visible on non-rotating rotational monitor 16 using rotational angle indicator 32 as described above, but may also be electronically transmitted to a suitable screen for visualization there as well. The system may also be appropriately configured for audible indications as well.

Referring now to FIG. 3, there is illustrated steerable ablation catheter 2 for ablating target tissue of a vessel of the body in accordance with another embodiment of the present disclosure. Steerable ablation catheter 2 includes catheter handle 10 and flexible elongate catheter body 4 having proximal end 6 and distal end 8. The length of steerable ablation catheter 2 is generally sufficient to access a target vessel of the body, such as a patient's renal artery, relative to a percutaneous access location. Steerable ablation catheter 2 also includes hub 12 operably connected to an inner lumen (not shown) within catheter handle 10 for insertion or delivery of catheter assemblies and wires. Steerable ablation catheter 2 further includes electrode 14 near distal end 8. Electrode 14 may be a single electrode, or may contain multiple electrodes as is known in the art. Catheter handle 10 is coupled to flexible elongate catheter body 4 such that a torque imparted to catheter handle 10 can be transmitted to flexible elongate catheter body 4, as well as to electrode 14 that is coupled to flexible elongate catheter body 4. Catheter handle 10 additionally includes microelectromechanical systems (MEMS) sensor 30, such as a MEMS sensor chip, which may include analog and/or digital technology for gathering and transmitting data. In one embodiment, the MEMS sensor chip includes a MEMS inertial sensor chip suitable for tracking, recording, and transmitting data related to rotational movement about an axis. Such MEMS inertial sensor chips are known to those of skill in the art.

MEMS sensor 30 is suitably configured and installed onto or near catheter handle 10 to electronically track, record, and transmit the rotational history of catheter handle 10 throughout an ablation procedure such that the rotational history of electrode 14 may also be known. MEMS sensor 30 may suitably be electronically connected and wired through steerable ablation catheter 2 (or may be connected wirelessly) such that the readings from MEMS sensor 30 may be transmitted to a visual medium for a doctor to monitor during a procedure. In this specific embodiment, as catheter handle 10 of steerable ablation catheter 2 is rotated during the procedure, the angle of rotation is electronically tracked, recorded, and transmitted to a suitable screen for visualization by the doctor such that the doctor can more accurately know the ablation history of electrode 14 in the body, and specifically in the artery. The system may also be appropriately configured for audible indications as well.

Referring now to FIG. 4, there is illustrated an ablation catheter system including steerable ablation catheter 2 for ablating target tissue of a vessel of the body in accordance with yet another embodiment of the present disclosure. Steerable ablation catheter 2 includes catheter handle 10 and flexible elongate catheter body 4 having proximal end 6 and distal end 8. The length of steerable ablation catheter 2 is generally sufficient to access a target vessel of the body, such as a patient's renal artery, relative to a percutaneous access location. Steerable ablation catheter 2 also includes hub 12 operably connected to an inner lumen (not shown) within catheter handle 10 for insertion or delivery of catheter assemblies and wires. Steerable ablation catheter 2 further includes electrode 14 near distal end 8. Electrode 14 may be a single electrode, or may contain multiple electrodes as is known in the art. Catheter handle 10 is coupled to flexible elongate catheter body 4 such that a torque imparted to catheter handle 10 can be transmitted to flexible elongate catheter body 4, as well as electrode 14 that is coupled to flexible elongate catheter body 4. The system additionally includes external motion detector 31 that is positioned to monitor, record, and transmit the rotational movement of catheter handle 10 during an ablation procedure. External motion detector 31 may be an analog motion detector or a digital motion detector. Suitable analog and digital motion detectors are known to those of skill in the art.

External motion detector 31 is suitably configured in conjunction with catheter handle 10 to electronically track, record, and transmit the rotational history of catheter handle 10 throughout an ablation procedure such that the rotational history of electrode 14 may also be known. External motion detector 31 may suitably be electronically connected such that the readings from external motion detector 31 are transmitted to a visual medium for a doctor to monitor during a procedure. In this specific embodiment, as catheter handle 10 of steerable ablation catheter 2 is rotated during the procedure, the angle of rotation is electronically tracked, recorded, and transmitted to a suitable screen for visualization by the doctor such that the doctor can more accurately know that ablation history of electrode 14 in the body, and specifically in the artery. The system may also be appropriately configured for audible indications as well. Although illustrated herein as an external motion detector, the present disclosure also contemplates a motion detected coupled directly to the steerable ablation catheter, and specifically on the catheter handle of the steerable ablation catheter.

The means for monitoring the rotational history of catheter handle 10 as set forth herein and specifically including non-rotating rotational monitor 16, MEMS sensor 30, and external motion detector 31, should desirably have an output proportional to the actual rotation angle of electrode 14 directed by catheter handle 10; that is, although the means for monitoring as described herein is monitoring the rotational history of catheter handle 10, the rotational angle output should be for electrode 14 as directed by catheter handle 10. As such, if the torque-ability of catheter handle 10 and electrode 14 is 1:1, the resulting rotational angle should so indicate and would be exactly that of catheter handle 10. If the torque-ability is other than 1:1, the rotational angle indicated should be appropriately calibrated to compensate for the difference to ensure accurate measurements of the circumferential ablation history.

In accordance with the present disclosure, the circumferential rotational history of catheter handle 10, and hence the circumferential ablation history of electrode 14 directed by catheter handle 10 and used to ablate the tissue, can be suitably used by a doctor not only to monitor the circumferential ablation history for an artery or other body area, but can also be used in combination with other information to generate a percent overall circumferential denervation of the of the artery. This can be done in real time during the ablation procedure, which is advantageous as the accuracy and completeness of the procedure can be improved as well as overall patient outcomes.

As noted herein, the present disclosure provides ablation catheters and systems, as well as methods of their use, for recording the rotational history of catheter handle 10, and hence the rotational ablation history of electrode 14 attached to and directed by catheter handle 10 and located within a vessel in the body. This information, along with knowledge of the average ablation spot size and the diameter of the vessel being ablated, may provide acute procedural success information to the doctor as to the overall percent denervation of the renal efferent and afferent nerves of the vessel.

For renal denervation procedures, the average ablation spot size on the vessel has a length of about 2 millimeters to about 5 millimeters, which corresponds generally to an area of about 3 square millimeters to about 20 square millimeters. The average diameter of the vessel is generally about 2 millimeters to about 12 millimeters, including from about 3 millimeters to about 10 millimeters, and including about 4 millimeters to about 8 millimeters. If a doctor knows the diameter of a vessel (D_(V)), the circumference of the vessel (C_(v)) can be calculated. By knowing the average diameter of ablation spots (D_(as)) (with respect to the circumference of the vessel), and the number of ablation spots (desirably at least 2, 3, 4, 5, 6, or more), the percent circumferential denervation of the vessel can be estimated using the following equation:

% Circumferential Denervation=100×[[(D _(as1) +D _(as2) +D _(as3)+ . . . )−(O _(ca))]/C _(v)]

wherein O_(ca) is the overlap of circumferential ablation as obtained from the rotational monitor means as described herein. This equation estimates the percent circumferential denervation while accounting for any circumferential overlap of the ablation spots, which is determined by the output of the rotational monitor means.

By allowing a doctor to have an estimation of the percent circumferential denervation of a vessel as calculated in real time during a procedure, the present disclosure allows a doctor to make necessary adjustments during a procedure to improve overall patient outcomes and improves the probability of achieving the desired percent denervation in a single procedure.

Although a number embodiments of this disclosure have been described above with a certain degree of particularity, those skilled in the art could make numerous alterations to the disclosed embodiments without departing from the spirit or scope of the disclosure. For example, an important feature of this disclosure is the rotational monitoring means used in combination with the catheter handle that directs the ablation electrode(s). One skilled in the art may modify the exact nature of the rotational monitoring means without departing from the spirit or scope of the disclosure. It is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative only and not limiting. Changes in detail or structure may be made without departing from the spirit of the disclosure as defined in the claims. 

What is claimed is:
 1. An ablation catheter system comprising a catheter handle, an elongate catheter body, an electrode, and a means for tracking a circumferential rotational history of the catheter handle.
 2. The ablation catheter of claim 1 wherein the means for tracking a circumferential rotational history of the catheter handle is a non-rotating rotational monitor attached to the catheter handle.
 3. The ablation catheter of claim 2 wherein the non-rotating rotational monitor has an output proportional to a rotational angle of the catheter handle.
 4. The ablation catheter of claim 2 wherein the non-rotating rotational monitor includes a series of markings indicating values for angles.
 5. The ablation catheter of claim 1 wherein the means for tracking a circumferential rotational history of the catheter handle is an electronic means.
 6. The ablation catheter of claim 5 wherein the electronic means includes a motion detector.
 7. The ablation catheter of claim 6 wherein the motion detector is external the ablation catheter.
 8. The ablation catheter of claim 5 wherein the electronic means includes a micro-electromechanical system.
 9. The ablation catheter of claim 8 wherein the micro-electromechanical system is external the ablation catheter.
 10. The ablation catheter of claim 1 wherein the ablation catheter is a single-electrode ablation catheter.
 11. The ablation catheter of claim 1 wherein the ablation catheter is a multi-electrode ablation catheter.
 12. A method for tracking the circumferential ablation history of a renal artery, the method comprising ablating at least two areas on the renal artery using an ablation system comprising an ablation catheter comprising a catheter handle, an elongate catheter body, an electrode, and a means for tracking a circumferential rotational history of the catheter handle, and recording the circumferential rotational history of the catheter handle for each ablation.
 13. The method of claim 12 wherein the ablation system further includes a means for projecting the recorded circumferential rotational history of the catheter handle onto a visual medium.
 14. The method of claim 12 wherein the means for tracking a circumferential rotational history of the catheter handle is a non-rotating rotational monitor attached to the catheter handle.
 15. The method of claim 14 wherein the non-rotating rotational monitor has an output proportional to a rotational angle of the catheter handle.
 16. The method of claim 15 wherein the non-rotating rotational monitor includes a series of markings indicating values for angles.
 17. The method of claim 12 wherein the means for tracking a circumferential rotational history of the catheter handle is an electronic means.
 18. The method of claim 17 wherein the electronic means includes a motion detector.
 19. The method of claim 18 wherein the motion detector is external the ablation catheter.
 20. A method for estimating the circumferential percent renal denervation for a renal artery, the method comprising performing at least two ablations on the renal artery using an ablation system comprising an ablation catheter comprising a catheter handle, an elongate catheter body, an electrode, and a means for recording a circumferential rotational history of the catheter handle, recording a circumferential angle for each ablation, and using an average ablation spot size, a diameter of the artery, and circumferential angle for each ablation to estimate the circumferential percent renal denervation for the artery. 